Hi,
I am looking for links to basic, simple, dumb, easy-to-use and set up, usable with internal soundcard, FFT SOFTWARE!!
All I need to do is to look at the SIGNAL sent from a line level device to see if it is FLAT (and not all that closely) across 20-20khz. No brainer, right?
I want to plug in the mini plug into a laptop, put the test signal on the device (externally generated) push a button and capture the signal on the sound card (ok I'll record it as a .wav if I have to) then FFT the result and see what it looks like.
(oh XP, PC)
ANY SUGGESTIONS??
_-_-bear
I am looking for links to basic, simple, dumb, easy-to-use and set up, usable with internal soundcard, FFT SOFTWARE!!
All I need to do is to look at the SIGNAL sent from a line level device to see if it is FLAT (and not all that closely) across 20-20khz. No brainer, right?
I want to plug in the mini plug into a laptop, put the test signal on the device (externally generated) push a button and capture the signal on the sound card (ok I'll record it as a .wav if I have to) then FFT the result and see what it looks like.
(oh XP, PC)
ANY SUGGESTIONS??
_-_-bear
VST is an acronym for "Virtual Studio Technology". It's a type of plugin for audio software that was developed by Steinberg.
There is a free audio editor called Audacity, which, in addition to being very useful piece of software, is also capable of using VST plugins such as the one mentioned:
http://audacity.sourceforge.net/about/features
There is a free audio editor called Audacity, which, in addition to being very useful piece of software, is also capable of using VST plugins such as the one mentioned:
http://audacity.sourceforge.net/about/features
Maybe these might be useful as well (I haven't personally used any of them):
http://www.etfacoustic.com/index.html
http://www.brownbear.de/toc.htm
http://www.zelscope.com/
http://www.etfacoustic.com/index.html
http://www.brownbear.de/toc.htm
http://www.zelscope.com/
Visual Analyser is free and works pretty well. I have trouble getting full duplex to work on a USB AD/DAC but it is fine just in measurement mode. It does 1/3 and less octave measurements too.
Thanks for the link to the Audacity plug in... it will likely work for my friend who is the one who needs to do this trick...
Still interested in what is available in freeware that will do this sort of thing... or more.
Tnx.
_-_-bear
Still interested in what is available in freeware that will do this sort of thing... or more.
Tnx.
_-_-bear
"Signal Analyzer" is another VST plugin that can do real-time FFT.
Also possibly useful is "VSTHost", which is solely for loading VST plugins.
Also possibly useful is "VSTHost", which is solely for loading VST plugins.
Sirp!
Free demo: Sirp
Available at
http://www.tolvan.com/
Another program: Tombstone
http://www.speech.kth.se/smptool/
/Jonas
Free demo: Sirp
Available at
http://www.tolvan.com/
Another program: Tombstone
http://www.speech.kth.se/smptool/
/Jonas
RMAA
http://audio.rightmark.org/index_new.shtml
in fact the quickest way to find your soundcard performance capbility is to google its model name and RMAA:
1st 2 resultrs google: esi juli@ RMAA
http://jimmyauw.com/2006/08/09/sound-card-comparison/
http://ixbtlabs.com/articles2/esi-julia/
http://audio.rightmark.org/index_new.shtml
in fact the quickest way to find your soundcard performance capbility is to google its model name and RMAA:
1st 2 resultrs google: esi juli@ RMAA
http://jimmyauw.com/2006/08/09/sound-card-comparison/
http://ixbtlabs.com/articles2/esi-julia/
What's your signal source? If it's a sweep you don't need FFT. Just record the sweep in Audacity (or anything else) and look at the envelope. If you really want to go the FFT route, you need a pink noise signal or the result won't be flat. Audacity will do that as well. Record a few seconds of pink noise signal than use the FFT function. I like Visual Analyzer a lot too. You can do pink noise (I think) and FFT with that as well.
Conrad,
I do not believe that your are correct about the results of doing and FFT on a sweep... I have done FFT on entire tracks of a CD and do not see a fall off with frequency. Perhaps I missed something when I did that.
_-_-bear
PS. In this case an audio friend of mine has a fancy type of LP playback (I won't go into details) and he acquired another suitably fancy computer program and test record to match that allegedly produces a curve that reflects the flatness of the output of said fancy LP playback system (cart + electronics box, FYI). The results he got are strange. So, the plan is to take a standard test record with a sweep and look at the output to see if it is also skewed in the same general manner as the original software. Since he already has a PC there, all he needs is to see the output of the sweep as a curve.
Yes, I suppose he can just look at the envelope of the wave as recorded in dB...
should have thought of that meeself! heh. The curve would be nice though.
I have yet to get over there and see what is going on...
Still, I want to find out about what freeware is out there - good to have that around and onhand, especially if one of them just happens to have a good interface and is easy and handy to use for various basic tasks...
I do not believe that your are correct about the results of doing and FFT on a sweep... I have done FFT on entire tracks of a CD and do not see a fall off with frequency. Perhaps I missed something when I did that.
_-_-bear
PS. In this case an audio friend of mine has a fancy type of LP playback (I won't go into details) and he acquired another suitably fancy computer program and test record to match that allegedly produces a curve that reflects the flatness of the output of said fancy LP playback system (cart + electronics box, FYI). The results he got are strange. So, the plan is to take a standard test record with a sweep and look at the output to see if it is also skewed in the same general manner as the original software. Since he already has a PC there, all he needs is to see the output of the sweep as a curve.
Yes, I suppose he can just look at the envelope of the wave as recorded in dB...
should have thought of that meeself! heh. The curve would be nice though.I have yet to get over there and see what is going on...
Still, I want to find out about what freeware is out there - good to have that around and onhand, especially if one of them just happens to have a good interface and is easy and handy to use for various basic tasks...
Have you looke at TrueRTA?
basic is free and is upgradable to 1/24oct
Link:
http://www.trueaudio.com/rta_abt1.htm[/ Sorry about link, but can always cut and paste
basic is free and is upgradable to 1/24oct
Link:
http://www.trueaudio.com/rta_abt1.htm[/ Sorry about link, but can always cut and paste
If you do an FFT on white noise, I think you're right, it should come out flat. If you do a 1/3 octave measurement (also available in Audacity and others) it will rise. Pink noise overcomes that and is usually preferable for physical acoustic measurements. For a line level electronic measurement I wouldn't bother with FFT, just look at the envelope of a sweep. It will probably be more accurate. Or, use the scope mode of Audacity and look directly at the waveform amplitude as it sweeps.
Many/most/some (I dunno) test LPs do not have flat recorded sweeps. The STR-100 rises from 20 to 500 Hz, and is flat from 500 to 20000. It was intended that one measure the signal with a voltmeter. I believe that was done to keep groove amplitudes under control. They give two tables, one pre eq and one after RIAA. Neither is supposed to be flat. Flat sweeps are usually of low amplitude and are more prone to error. There weren't any handy computer FFTs back then, so they didn't even consider it! If you've ever measured signals from an LP, it's messy business compared to a real signal generator or digital methods. Lots of instability in both amplitude and frequency no matter how fancy the playback system is.
Many/most/some (I dunno) test LPs do not have flat recorded sweeps. The STR-100 rises from 20 to 500 Hz, and is flat from 500 to 20000. It was intended that one measure the signal with a voltmeter. I believe that was done to keep groove amplitudes under control. They give two tables, one pre eq and one after RIAA. Neither is supposed to be flat. Flat sweeps are usually of low amplitude and are more prone to error. There weren't any handy computer FFTs back then, so they didn't even consider it! If you've ever measured signals from an LP, it's messy business compared to a real signal generator or digital methods. Lots of instability in both amplitude and frequency no matter how fancy the playback system is.
Tombstone
Tombstone is not a FFT gadget, it makes a response curve just
like the good old chart recorders by sweeping a sinus signal.
I prefer this program (I have tested quite a few) as I think its the only one that corresponds with what I hear.
Best of all, it's free at: http://www.speech.kth.se/smptool/
Tombstone is not a FFT gadget, it makes a response curve just
like the good old chart recorders by sweeping a sinus signal.
I prefer this program (I have tested quite a few) as I think its the only one that corresponds with what I hear.
Best of all, it's free at: http://www.speech.kth.se/smptool/
This is a nice app with both a scope, xy and fft.
http://zeitnitz.de/Christian/Scope/Scope_en.html
another app by the same author that might be useful(I have not tested it though).
http://zeitnitz.de/Christian/WaveIO/waveio.html
http://zeitnitz.de/Christian/Scope/Scope_en.html
another app by the same author that might be useful(I have not tested it though).
http://zeitnitz.de/Christian/WaveIO/waveio.html
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